JP6004731B2 - Run flat tire - Google Patents

Description

  The present invention relates to a run-flat tire (hereinafter also simply referred to as “tire”), and more particularly, to a run-flat tire according to an improvement in a reinforcing cord used for a carcass ply.

  Polyethylene terephthalate (PET) has high strength per weight and is inexpensive, so it is used as a general-purpose cord for tire reinforcement. When a cord made of organic fibers such as PET is used as a tire reinforcing material, generally, after the cord is dipped in an adhesive such as a resorcin / formalin / latex (RFL) adhesive, Coat and apply to tire as rubber-cord composite. However, since the surface of polyester fiber such as PET has few reactive sites due to its chemical structure, it is difficult to ensure the adhesive force between the filament and the adhesive in the composite process of cord and rubber. there were.

  As a technique for further improving the adhesion between PET and rubber, in addition to a method in which a PET cord is pretreated with an epoxy compound and then treated with an RFL adhesive, for example, Patent Document 1 discloses that PET is bonded with epoxy. A two-bath dipping process is disclosed in which the film is once immersed in an agent and then immersed again in an RFL adhesive. Further, improvement of epoxy adhesives has also been studied. For example, Patent Document 2 discloses a water-soluble polymer, an organic polyisocyanate containing a structure in which aromatics are methylene-bonded, and a plurality of active hydrogens. An epoxy-based adhesive composition containing an aqueous urethane compound obtained by reacting a compound having a thermal decomposition with a component containing a heat dissociable blocking agent is disclosed.

JP 2000-355875 A JP 2001-98245 A

  Conventionally, in a run-flat tire in which polyester fibers are applied to a carcass ply, the carcass ply peels and breaks at the tire side part during run-flat running, and the tire may fail early. This is considered to be due to insufficient adhesion between the polyester fiber and the rubber.

  According to the two-bath treatment proposed in Patent Document 1 and the epoxy adhesive composition proposed in Patent Document 2, the adhesion between PET and rubber can be improved. When using tires in a heavy load environment, it was not sufficient. Further, it is conceivable to improve the adhesiveness by hybridization with other fibers, but there is a problem that sufficient adhesiveness cannot be secured between PET and the other fibers. Therefore, the use of a reinforcing cord having stronger adhesiveness under the input of dynamic strain, particularly heat resistant adhesiveness, with the rubber prevents the carcass ply from being peeled and broken. There has been a demand for realizing a tire with improved flat durability performance.

  Accordingly, an object of the present invention is to provide a run-flat tire having improved run-flat durability performance by improving a carcass ply reinforcement cord.

  As a result of earnest study, the present inventor used a hybrid cord composed of nylon fiber or cellulose fiber having good adhesion to rubber as a reinforcing cord of the carcass ply and a polyester fiber subjected to a specific pretreatment, The present inventors have found that the adhesive force between rubber and the rubber under the input of dynamic strain can be dramatically improved, thereby completing the present invention.

That is, the present invention includes a pair of left and right bead portions, a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction, and a tread portion that extends between the pair of sidewall portions to form a ground contact portion. A carcass composed of one or more carcass plies that extend in a toroidal shape between the pair of bead portions and reinforce each of the portions, and a crescent-shaped cross section disposed inside the carcass in the sidewall portion In a run flat tire provided with a side reinforcing rubber layer,
The carcass ply comprises a rubberized layer of a hybrid cord formed by twisting a filament made of polyester fiber and a filament made of nylon fiber or cellulose fiber,
The polyester fiber is a fiber made of polyester having an intrinsic viscosity of 0.85 or more, the main repeating unit of which is ethylene terephthalate, and the amount of terminal carboxy groups in the polyester fiber is 20 equivalents / ton or more. The long period by X-ray small angle diffraction of the fiber is 9-12 nm, and
A surface treatment agent having an epoxy group is adhered to the fiber surface of the polyester fiber.

In the present invention, it is preferable that the terminal carboxy groups of the fiber surface of the polyester fibers is less than 10 equivalents / ton, the crystal size of the fiber transverse axis direction of the polyester fibers to be 35～80Nm ² preferable. Furthermore, the amount of terminal methyl groups in the fiber of the polyester fiber is preferably 2 equivalent / ton or less, and the content of titanium oxide in the fiber of the polyester fiber is preferably 0.05 to 3.0 mass. The epoxy index on the fiber surface of the polyester fiber is preferably 1.0 × 10 ⁻³ equivalent / kg or less.

  Furthermore, in the present invention, it is preferable that the hybrid cord is coated with a resorcin / formaldehyde / latex adhesive composition, and the total fineness of the hybrid cord is preferably 2000 dtex or more and 5100 dtex or less.

  According to the present invention, with the above-described configuration, it is possible to realize a run flat tire with improved run flat durability performance.

It is a width direction one side sectional view showing an example of the run flat tire of the present invention. It is process drawing which shows the preparation methods of the cord for tire reinforcement which concerns on an Example.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows a cross-sectional side view in one width direction of an example of the run flat tire of the present invention. As shown in the figure, the run-flat tire of the present invention includes a pair of left and right bead portions 1, a pair of sidewall portions 2 that extend from the bead portion 1 to the outside in the tire radial direction, and a pair of sidewall portions 2. A carcass 4 having one or more carcass plies that have a tread portion 3 that extends and forms a ground contact portion, extends in a toroidal shape between a pair of bead portions 1 and reinforces each of these portions 1, 2, 3; A side reinforcing rubber layer 5 having a crescent-shaped cross section disposed inside the carcass 4 in the sidewall portion 2.

  Further, in the illustrated tire, a bead filler 7 is disposed on the outer side in the tire radial direction of the ring-shaped bead core 6 embedded in the bead portion 1, and on the outer side in the tire radial direction of the crown portion of the carcass 4, A belt 8 composed of two belt layers is disposed. Further, on the outer side in the tire radial direction of the belt 8, a belt reinforcing layer (cap layer) 9A covering the entire belt 8, and a pair of belt reinforcing layers (layer layers) 9B covering only both ends of the belt reinforcing layer 9A, Is arranged.

  In the present invention, the carcass ply is composed of a rubberized layer of a hybrid cord formed by twisting a filament made of polyester fiber and a filament made of nylon fiber or cellulose fiber, and an epoxy group is formed on the fiber surface of the polyester fiber. It is important that the surface treatment agent having Hybrid cord made of polyester fiber and nylon fiber or cellulose fiber uses polyester fiber that has been treated with an epoxy-based surface treatment agent to provide adhesion between the two fibers that make up the hybrid cord. While ensuring, it became possible to make a cord having stronger adhesiveness under the input of dynamic strain, particularly heat-resistant adhesiveness, with rubber. As a result, the bond between the hybrid cord and rubber is made uniform, and the occurrence of cord breakage can be suppressed, so in the tire using such a hybrid cord as a carcass ply reinforcement cord, the generation of separation nuclei during run-flat running is suppressed. Thus, it is possible to prevent the carcass ply from being peeled and broken, and as a result, it is possible to realize a run-flat tire with improved run-flat durability performance.

  The polyester fiber used in the present invention only needs to be pretreated with a surface treatment agent having an epoxy group, and the polyester itself constituting the polyester fiber is conventionally known, for example, from various commercially available products. It can be appropriately selected and used, and is not particularly limited. As such a polyester fiber, in particular, those having specific physical properties described in detail below can be suitably used.

  The polyester fiber suitable for the present invention is a fiber made of polyester having ethylene terephthalate as a main repeating unit and an intrinsic viscosity of 0.85 or more, and the amount of terminal carboxy groups in the fiber is 20 equivalents / ton or more. The long period by X-ray small angle diffraction is 9-12 nm, and the surface treatment agent which has an epoxy group adheres to the fiber surface.

  The intrinsic viscosity of the polyester fiber needs to be 0.85 or more, and preferably 1.10 or less. More preferably, a polyester fiber having an intrinsic viscosity of 0.90 to 1.00 is used. When the intrinsic viscosity is less than 0.85, the strength of the polyester fiber is not sufficient, and in particular, the strength reduction in the tire vulcanization process cannot be sufficiently suppressed.

  Moreover, in the said polyester fiber, the amount of terminal carboxy groups of the whole polymer needs to be 20 equivalent / ton or more. Conventionally, in a polyester fiber generally used for tire reinforcement, for the purpose of improving the heat deterioration resistance, it has been a general technique to keep the carboxy group of the polymer at 15 equivalents / ton or less. However, since the polyester fiber for tire reinforcement has a high need for maintaining adhesion to rubber in addition to maintaining the strength of the fiber, the long period by X-ray small angle diffraction is 9 to 12 nm as in the polyester fiber according to the present invention. When the surface is epoxy-treated, a carboxy group amount of 20 equivalents / ton or more is most suitable for tire reinforcement. The upper limit of the amount of carboxy groups in the polymer is preferably 40 equivalents / ton or less, and more preferably 21 to 25 equivalents / ton.

  Furthermore, in the said polyester fiber, it is necessary for the long period by X-ray small angle diffraction to be 9-12 nm. The long period by X-ray small angle diffraction here means the space | interval of the crystal | crystallization in the polyester polymer of a fiber longitudinal direction. This long period in the polyester fiber according to the present invention is characterized by a short point, and the number of tie molecules connecting the crystals increases, resulting in a high cooperation maintenance rate when used as a tire reinforcing fiber. You can keep it. Further, by setting the long period in the above range, the physical properties of the fibers can be made suitable for high modulus and low shrinkage tire reinforcing fibers. In general, the lower limit of the long period range is 9 nm. Suitably, the long period by the X-ray small angle diffraction of the said polyester fiber shall be the range of 10-11 nm.

  In the present invention, the amount of terminal carboxy groups on the fiber surface (raw yarn surface) of the polyester fiber is preferably 10 equivalents / ton or less. The carboxy group amount of the whole polymer in the polyester fiber according to the present invention is required to be 20 equivalents / ton or more as described above, but the carboxy group amount on the fiber surface is an epoxy compound attached to the fiber surface. It is preferable that it is below 10 equivalent / ton or less by reaction with this. Thus, when the carboxy group in the polymer reacts with the epoxy group on the fiber surface, the polyester resin according to the present invention has extremely excellent adhesive performance. At this time, if the amount of terminal carboxy groups on the fiber surface is excessively large, heat resistance and adhesiveness tend to decrease.

Further, the polyester fiber is preferably crystal size of the fiber transverse direction is in the range of 35~80nm ^2. The polyester fiber according to the present invention has a short period of 12 nm or less, which is the interval between crystals on the longitudinal axis of the fiber. However, in order to obtain a high-strength fiber, the size of the crystal is also necessary. The crystal size in the horizontal axis direction is preferably grown to 35 nm ² or more. However, even if the crystal size is too large, the fiber becomes stiff and the fatigue property is lowered. Therefore, the crystal size is preferably 80 nm ² or less. The crystal size in the fiber horizontal axis direction is more preferably in the range of 40 to 70 nm ² . As described above, the crystal grows in the horizontal axis direction of the fiber, so that the tie molecules easily develop in the horizontal axis direction of the fiber, so that a three-dimensional structure is constructed in the vertical and horizontal direction of the fiber for tire reinforcement. It becomes a particularly suitable fiber. Furthermore, by taking such a three-dimensional structure, the loss factor tan δ of the fiber is lowered. As a result, the amount of heat generated under repeated stress can be suppressed, and the adhesion performance after applying repeated stress can be kept high, which makes the fiber particularly preferable for tire reinforcement applications.

  Furthermore, in the said polyester fiber, it is preferable that the amount of terminal methyl groups in the fiber is 2 equivalent / ton or less, More preferably, a terminal methyl group shall not be contained. This is because the methyl group in the polyester polymer has low reactivity and does not react with the epoxy group at all, and therefore tends to inhibit the reaction between the carboxy group and the epoxy group effective for improving the adhesiveness. If the polymer constituting the fiber has no or few terminal methyl groups, high reactivity with the epoxy group in the surface treatment agent is ensured, and high adhesion and surface protection performance can be ensured. It becomes possible.

  Furthermore, in the said polyester fiber, it is preferable that the titanium oxide content in a fiber is 0.05-3.0 mass%. When the titanium oxide content is less than 0.05% by mass, the smoothing effect for dispersing the stress acting between the roller and the fiber in the stretching process or the like tends to be insufficient. There is a risk of increasing the strength. On the other hand, when the content of titanium oxide is more than 3.0% by mass, the titanium oxide acts as a foreign substance inside the polymer to obstruct stretchability, and the strength of the finally obtained fiber tends to decrease. .

Furthermore, in the said polyester fiber, it is preferable that the epoxy index in the fiber surface is 1.0 * 10 < ^-3 > equivalent / kg or less. In particular, the epoxy index per kg of the polyester fiber is preferably 0.01 × 10 ^{−3 to} 0.5 × 10 ⁻³ equivalent / kg. When the epoxy index of the fiber surface is high, there is a tendency that there are many unreacted epoxy compounds. For example, a large amount of viscous scum is generated in the twisting process, and the processability of the fiber decreases. At the same time, there arises a problem that causes a decrease in product quality such as twisted yarn spots.

  The strength of the polyester fiber is preferably in the range of 4.0 to 10.0 cN / dtex. If the strength is too low or too high, the end result tends to be inferior in durability in rubber. For example, if production is performed with a very high strength, yarn breakage tends to occur in the yarn making process, and there is a tendency for quality stability as industrial fibers to occur. Moreover, it is preferable that the dry heat shrinkage rate at 180 ° C. of the fiber is in the range of 1 to 15%. If the dry heat shrinkage is too high, the dimensional change during processing tends to be large, and the dimensional stability of a molded product using fibers tends to be inferior.

  Here, in this invention, as a surface treating agent which has an epoxy group attached to the surface of a polyester fiber, the epoxy compound which is 1 type or the mixture of 2 or more types of the epoxy compound which has 2 or more of epoxy groups in 1 molecule The one containing is preferred. More specifically, halogen-containing epoxies are preferred, and examples include those obtained by synthesis with epichlorohydrin polyhydric alcohols or polyhydric phenols, and compounds such as glycerol polyglycidyl ether are preferred. The adhesion amount of the surface treatment agent containing such an epoxy compound to the fiber surface is in the range of 0.05 to 1.5 mass%, preferably 0.10 to 1.0 mass%. The surface treatment agent may be mixed with a smoothing agent, an emulsifier, an antistatic agent, other additives and the like as necessary.

  There is no restriction | limiting in particular as a cellulose fiber used for this invention, Rayon, a lyocell, a cupra etc. can be mentioned. Examples of nylon fibers include 66 nylon, 6 nylon, 4, 6 nylon, and the like.

  The hybrid cord according to the present invention is subjected to an adhesive treatment after being twisted together. The adhesive composition used in the present invention is not particularly limited. For example, various adhesive compositions conventionally known in the field of organic fiber cords for tire reinforcing materials, such as general-purpose RFL adhesive compositions, are used. Can be used. The hybrid cord according to the present invention has an advantage in that adhesiveness can be secured only by an adhesive treatment using a normal RFL adhesive composition without using a special adhesive composition. .

  The adhesive treatment using the adhesive composition can be performed according to a conventional method, and is not particularly limited. Methods for coating the cord with the adhesive composition include dipping the cord in the adhesive composition, applying the adhesive composition with a brush, and spraying the adhesive composition. An appropriate method can be selected accordingly. The method for coating the cord surface with the adhesive composition is not particularly limited, but when the cord composition is coated on the cord surface, the adhesive composition is dissolved in various solvents to reduce the viscosity. Since application | coating becomes easy, it is preferable. Moreover, it is environmentally preferable that this solvent consists mainly of water.

  The cord after coating with the adhesive composition can be dried, for example, at a temperature of 100C to 210C. Thereafter, the subsequent heat treatment is performed at a temperature not lower than the glass transition temperature of the polymer of the resin material constituting the cord, preferably not lower than [melting temperature−70 ° C.] and not higher than [melting temperature−10 ° C.]. preferable. The reason for this is that the molecular mobility of the polymer is poor below the glass transition temperature of the polymer, and the adhesive composition and resin cannot be sufficiently interacted with the component that promotes adhesion in the adhesive composition. This is because the bonding strength with the material cannot be obtained. Such a resin material may be pretreated by an electron beam, microwave, corona discharge, plasma treatment or the like in advance. Further, the dry weight of the adhesive composition covering the cord is preferably 0.5 to 6.0 mass% with respect to the cord weight.

  As described above, a treat in which the cord and the rubber are firmly bonded to each other by a method such as embedding the reinforcing cord obtained by subjecting the hybrid cord to an adhesive treatment in an unvulcanized rubber and vulcanizing it. By applying this to the carcass ply, the tire of the present invention can be obtained.

  In the present invention, the total fineness of the hybrid cord is preferably 2000 dtex or more and 5100 dtex or less. If the total fineness is less than 2000 dtex, the cord strength is insufficient, and if it exceeds 5100 dtex, unevenness occurs in the tire side portion, which is not preferable in any case.

  In the run-flat tire of the present invention, only the point that satisfies the conditions relating to the carcass ply cord is important, and the details of the tire structure and the material of each member other than that are not particularly limited, It can be configured by appropriately selecting from among them.

  For example, the carcass 4 is composed of one carcass ply formed by coating a plurality of carcass ply cords arranged in parallel with a coating rubber, and in the illustrated example, between the pair of bead cores 6 embedded in the bead portion 1. A toroid-like main body portion and a folded portion wound around the bead core 6 from the inner side to the outer side in the tire width direction outward in the tire radial direction. The number of plies and the structure of 4 are not limited to this. In the present invention, in any case, it is necessary to apply the polyester cord to all carcass plies. In the present invention, the number of the polyester cords driven into the carcass ply 2 can be 35 to 65/50 mm.

  The belt layer is usually composed of a rubberized layer of a cord extending at an angle of 10 ° to 40 ° with respect to the tire equatorial plane, preferably a rubberized layer of a steel cord. The belt 8 is formed by laminating the cords constituting the layers so as to cross each other with the equator plane interposed therebetween. In the illustrated example, the belt 8 includes two belt layers. However, in the pneumatic tire of the present invention, the number of belt layers constituting the belt 8 is not limited to this. Further, the belt reinforcing layers 9A and 9B are usually made of rubberized layers of cords arranged substantially parallel to the tire circumferential direction. However, in the present invention, the belt reinforcing layers 9A and 9B are not necessarily provided. Alternatively, a belt reinforcing layer having a different structure may be provided.

  Furthermore, in the tire of the present invention, a tread pattern is appropriately formed on the surface of the tread portion 3, and an inner liner (not shown) is formed in the innermost layer. Furthermore, in the tire of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Example 1>
<Preparation of polyester fiber (1)>
By using a polyethylene terephthalate chip having an intrinsic viscosity of 1.03 and having a high carboxy group terminal, high-speed spinning and multistage stretching are performed by a melt spinning method, and the surface is subjected to an epoxy treatment, whereby the following polyester fiber (1) is obtained. Got ready. The oil agent used for the epoxy treatment adhered to 0.2 parts by mass with respect to 100 parts by mass of the fiber, and the amount of polyglycerol polyglycidyl ether, which is an epoxy compound component, was 0.12% by mass. It was.

This polyester fiber (1) has mechanical properties of an intrinsic viscosity of 0.91, fineness of 1130 dtex, 384 filament, strength of 6.9 cN / dtex, elongation of 12%, and dry heat shrinkage of 10.5%. The amount of terminal carboxy groups is 22 equivalents / ton, the long period by X-ray small angle diffraction is 10 nm, the amount of terminal carboxy groups on the fiber surface is 7 equivalents / ton, the crystal size in the fiber transverse axis direction is 45 nm ² , and terminal methyl The base amount was 0 equivalent / ton, the titanium oxide content was 0.05 mass%, and the surface epoxy group amount (epoxy index) was 0.1 × 10 ⁻³ equivalent / kg.

  Here, the intrinsic viscosity, strength and elongation of the polyester fiber, dry heat shrinkage rate, terminal carboxy group amount, long period by X-ray small angle diffraction and crystal size in the fiber transverse axis direction, terminal carboxy group amount on the fiber surface, terminal The methyl group content, titanium oxide content, and surface epoxy group content were measured according to the following. The same applies to the following.

<Intrinsic viscosity>
The diluted solution which melt | dissolved the polyester chip | tip and the polyester fiber in orthochlorophenol in 100 degreeC for 60 minutes was calculated | required from the value measured using the Ubbelohde viscometer at 35 degreeC.

<Amount of terminal carboxy group>
40.00 g of the polyester sample powdered using a pulverizer and 100 ml of benzyl alcohol were added to the flask, and the polyester sample was dissolved in benzyl alcohol under a nitrogen stream at 215 ± 1 ° C. for 4 minutes. After dissolution, the sample solution is allowed to cool to room temperature, and then an appropriate amount of 0.1% by mass phenol red benzyl alcohol is added and titrated quickly with N normal sodium hydroxide in benzyl alcohol until discoloration occurs. The amount of dripping was Aml. As a blank, add the same amount of 0.1% by weight of phenol red benzyl alcohol to 100 ml of benzyl alcohol, quickly titrate with N normal sodium hydroxide benzyl alcohol solution, and add the amount of dripping until discoloration occurs. Bml. From these values, the terminal COOH group content in the polyester sample was calculated by the following formula.
COOH end group content ^{(eq / 10 0 g) =} (A-B) × 10 3 × N × 10 6/40
The benzyl alcohol used here is a reagent-grade grade distilled and stored in a light-shielding bottle. As the N normal sodium hydroxide solution of benzyl alcohol, a solution obtained by titrating with a sulfuric acid solution having a known concentration in advance by a conventional method and obtaining the normality N accurately was used.

<Amount of terminal methyl group>
The polyester was hydrolyzed to acid component and glycol component, and then the methyl ester component was quantified by gas chromatography and calculated from this value.

<Titanium oxide content>
The content of each element was measured using a fluorescent X-ray apparatus (manufactured by Rigaku Corporation, Model 3270E), and quantitative analysis was performed. In the case of this fluorescent X-ray analysis, while a polyester fiber resin polymer sample was heated at 260 ° C. for 2 minutes with a compression press machine, a test molded body having a flat surface was produced under a pressure of 7 MPa, Measurements were performed.

<X-ray diffraction>
The X-ray diffraction of the polyester composition / fiber was performed using an X-ray diffractometer (manufactured by Rigaku Corporation, RINT-TTR3, Cu-Kα ray, tube voltage 50 kV, current 300 mA, parallel beam method). The long period interval is a diffraction line of meridian interference obtained by using a X-ray small angle scattering measurement device and irradiating at a right angle to the fiber axis using a Cu-Kα ray having a wavelength of 1.54 mm as a radiation source. From this, it was calculated using the Bragg equation. The crystal size was determined from the X-ray wide angle diffraction using the half-width of the (010) (100) intensity distribution curve of the equator scan using the shirare equation.

<Amount of terminal carboxy group on fiber surface>
According to JIS K0070-3.1 neutralization titration method, the amount of carboxy groups (acid value) on the fiber surface was determined. That is, 50 ml of diethyl ether / ethanol = 1/1 solution was added to about 5 g of a fiber sample, a few drops of a phenolphthalein solution was added as an indicator, and ultrasonically shaken at room temperature for 15 minutes. This solution was titrated with a 0.1 ml potassium hydroxide ethanol solution (factor value f = 1.030), and the indicator dripping amount was measured when the indicator continued to light red for 30 seconds. The value was calculated.
Acid value A (eq / ton) = (B × 1.030 × 100) / S
(Here, B represents 0.1 ml potassium hydroxide ethanol solution titration (ml), and S represents the sample amount (g))

<Fiber strength and elongation>
It measured according to JIS L-1013 using the tensile load measuring device (Shimadzu Corporation autograph).

<Dry heat shrinkage>
According to JIS-L1013, after being left for 24 hours in a room where the temperature and humidity are controlled at 20 ° C. and 65% RH, it was heat-treated in a dryer at 180 ° C. for 30 minutes, and calculated from the difference in test length before and after the heat treatment. .

<Epoxy index (EI)>
About the polyester fiber after a heating process, the epoxy index | exponent (EI: epoxy equivalent number per kg of fiber) was measured according to JISK-7236.

  In accordance with the conditions shown in Table 2 below, a filament made of polyester fiber (1) and a filament made of nylon fiber were twisted together to obtain a hybrid cord.

  Next, an RFL adhesive solution was prepared with the formulation shown in Table 1 below, and this adhesive solution was diluted and adjusted to a 20 mass% adhesive aqueous solution at the above ratio. The blocked isocyanate compound was added immediately before use after blending an RFL adhesive solution and aging at 20 ° C. for 24 hours. The blocked isocyanate compounds used are Daiseki Kogyo Seiyaku Co., Ltd .: Elastron BN69 (blocking agent separation temperature 120 ° C.) and BN27 (blocking agent separation temperature 180 ° C.). The latex was made by emulsion polymerization.

  The hybrid cord was subjected to an adhesive treatment using the adhesive liquid in the step shown in FIG. Specifically, the cord 102 delivered from the unwinding device 101 is passed through the adhesive solution 103, the cord 102 is impregnated with the adhesive solution 103 (impregnation step), and the impregnated cord 102 is sent to the drying zone 104. The cord 102 was dried (drying step), and the dried cord 102 was passed through the heat setting zone 105 and the normalizing zone 106 (heat treatment step), and then the cord 102 was cooled and wound by the winding device 107. The drying temperature of the drying zone 104 in the drying step was the temperature shown in the above table, and the drying time was 2 minutes. In the subsequent heat treatment step including the heat setting zone 105 and the normalizing zone 106, the treatment temperature was 250 ° C. and the treatment time was 1 minute. At this time, the cord tension was 1 kg / piece.

  The obtained adhesive-treated hybrid cord was covered with rubber to produce a treat with 50 shots / 50 mm, and this was applied to a carcass ply of a run-flat tire with a tire size of 245 / 45R19. A test tire was produced. The test tire has a pair of left and right bead portions, a pair of sidewall portions that extend from the bead portion to the outside in the tire radial direction, and a tread portion that extends between the pair of sidewall portions to form a ground contact portion. A carcass made of a single layer of carcass ply that extends in a toroidal shape between a pair of bead portions and reinforces each of the portions, and a side reinforcing rubber layer having a crescent-shaped cross section disposed inside the carcass in the side wall portion. It was equipped with. Further, on the outer side in the tire radial direction of the crown portion of the carcass, a belt (material: steel) composed of two belt layers arranged in an intersecting manner at an angle of ± 40 ° with respect to the tire circumferential direction and the entire belt are covered. One cap layer and a pair of layer layers covering only both ends of the belt were included.

<Examples 2 to 5>
Test tires of Examples 2 to 5 were produced in the same manner as in Example 1 except that the hybrid cord conditions were changed according to Table 2 below.

<Example 6>
As polyester fiber, polyester fiber (2) (PET with epoxy surface treatment) was used instead of polyester fiber (1), and the conditions of the hybrid cord were changed according to Table 2 below, and the same as in Example 1. Thus, a test tire of Example 6 was produced.

<Comparative Example 1>
The polyester fiber (2) was used as the polyester fiber, and a filament made of the polyester fiber (2) was twisted according to the following Table 3 to obtain a polyester cord.

  Next, Epocros K1010E (manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 40% by mass, acrylic / styrene copolymer emulsion containing 2-oxazoline group, polymer Tg: −50 ° C., oxazoline group amount: 0.9 (Mmol / g, solid)) 5% by mass, Isoban 10 (manufactured by Kuraray Co., Ltd., solid content concentration 100% by mass, copolymer of isobutylene and maleic anhydride, molecular weight: 160,000 to 170,000) 15 % By mass, DELION PAS-037 (manufactured by Takemoto Yushi Co., Ltd., diphenylmethane bis (4,4′-carbamoyl-ε-caprolactam): solid content concentration 27.5% by mass containing the molecular structure of diphenylmethane diisocyanate and blocking agent ) 20% by mass, and Denacor EX614B (manufactured by Nagase Kasei Kogyo Co., Ltd., sorbitol poly) The glycidyl ether) consisting of 60 wt% epoxy adhesive composition was prepared. The polyester cord was subjected to an adhesive treatment with this epoxy adhesive composition, and then further subjected to an adhesive treatment with a general-purpose RFL adhesive composition.

  A test tire of Comparative Example 1 was fabricated in the same manner as in Example 1 except that the obtained adhesive-treated polyester cord was used instead of an adhesive-treated hybrid cord.

<Comparative example 2>
A polyester cord (1) was twisted according to the following Table 3 to obtain a polyester cord. The polyester cord was subjected to an adhesive treatment with the RFL adhesive solution used in Example 1. A test tire of Comparative Example 2 was produced in the same manner as Example 1 except that the obtained adhesive-treated polyester cord was used instead of an adhesive-treated hybrid cord.

<Examples 7 and 8>
Test tires of Comparative Examples 3 and 4 were produced in the same manner as in Example 1 except that the hybrid cord conditions were changed according to Table 3 below.

  About each obtained test tire, according to the following, run flat drum durability, the unevenness | corrugation of a side part, and cut property were evaluated. The obtained results are also shown in Tables 2 and 3 below.

<Runflat drum durability>
A comparative example in which a drum test was performed in an environment of a load of 4.17 kN, a speed of 89 km / h, and a temperature of 38 ° C. without filling the test tires with internal pressure, and the mileage until the tire failed was measured. The travel distance up to the failure of one tire was taken as 100 and indicated as an index. The larger the index value, the longer the distance traveled until failure and the better the run-flat durability. In addition, the form of destruction at the time of failure was observed.

<Unevenness on the side>
For each of the test tires, when the internal pressure was 180 kPa, the unevenness of the tire side portion was measured with a laser, and the peak value was digitized to evaluate the dent. The results are shown as an index with Comparative Example 1 as 100. It can be said that the larger the value, the larger the dent and the worse the result.

<Cutability>
Each test tire is assembled on the specified rim, filled with the specified internal pressure, the convex protrusion with the radius of curvature R = 10 (mm) at the tip is pressed against the side, and the side is cut The required work was measured. The results are shown as an index with the amount of work required to reach the side cut of the tire of Comparative Example 1 as 100. The larger the value, the better the side cut performance.

＊１）ポリエステル繊維（１）
＊２）ポリエステル繊維（２）

* 1) Polyester fiber (1)
* 2) Polyester fiber (2)

  As shown in the above table, in the test tires of each example, the occurrence of carcass ply peeling failure during run flat running is suppressed without impairing other performance, thereby achieving run flat durability performance. Has been confirmed to improve.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass 5 Side reinforcement rubber layer 6 Bead core 7 Bead filler 8 Belt 9A, 9B Belt reinforcement layer 101 Unwinding apparatus 102 Cord 103 Adhesive liquid 104 Drying zone 105 Heat set zone 106 Normalizing Thorn 107 Winding device

Claims (8)

A pair of left and right bead portions; a pair of sidewall portions that are continuous from the bead portion to the outside in the tire radial direction; and a tread portion that extends between the pair of sidewall portions to form a grounding portion, A carcass made of one or more carcass plies extending in a toroidal shape between the bead portions of the carcass plies, and a side reinforcing rubber layer having a crescent-shaped cross section disposed inside the carcass in the sidewall portion. In a run flat tire comprising
Said carcass ply, Ri Do rubberized layer of hybrid cord formed by twisting a filament made of the filament and the nylon fibers or cellulose fibers made of polyester fibers,
The polyester fiber is a fiber made of polyester having an intrinsic viscosity of 0.85 or more, the main repeating unit of which is ethylene terephthalate, and the amount of terminal carboxy groups in the polyester fiber is 20 equivalents / ton or more. The long period by X-ray small angle diffraction of the fiber is 9-12 nm, and
Run flat tires, characterized in that the fiber surface of the polyester fibers, formed by adhering a surface treatment agent having an epoxy group. Run-flat tire according to claim 1, wherein the terminal carboxy group content is less than 10 equivalents / ton of fiber surface of the polyester fibers. The run-flat tire according to claim 1 or 2, wherein the crystal size of the fiber transverse axis direction of the polyester fiber is 35～80Nm ^2. The run-flat tire according to any one of claims 1 to 3 , wherein the amount of terminal methyl groups in the fiber of the polyester fiber is 2 equivalent / ton or less. The run flat tire according to any one of claims 1 to 4 , wherein a content of titanium oxide in the fiber of the polyester fiber is 0.05 to 3.0 mass%. The run-flat tire according to any one of claims 1 to 5 , wherein an epoxy index of a fiber surface of the polyester fiber is 1.0 x ^10-3 equivalent / kg or less. The run-flat tire according to any one of claims 1 to 6 , wherein the hybrid cord is coated with a resorcin / formaldehyde / latex adhesive composition. The run-flat tire according to any one of claims 1 to 7 , wherein a total fineness of the hybrid cord is 2000 dtex or more and 5100 dtex or less.

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